Replacing NULL with 0 in a SQL server query

Question

I have developed a query, and in the results for the first three columns I get NULL. How can I replace it with 0?

  Select c.rund         


        

Answer 1

Use COALESCE, which returns the first not-null value e.g.

SELECT COALESCE(sum(case when c.runstatus = 'Succeeded' then 1 end), 0) as Succeeded

Will set Succeeded as 0 if it is returned as NULL.

Answer 2

When you say the first three columns, do you mean your SUM columns? If so, add ELSE 0 to your CASE statements. The SUM of a NULL value is NULL.

sum(case when c.runstatus = 'Succeeded' then 1 else 0 end) as Succeeded, 
sum(case when c.runstatus = 'Failed' then 1 else 0 end) as Failed, 
sum(case when c.runstatus = 'Cancelled' then 1 else 0 end) as Cancelled, 

• SQL Fiddle Demo

Answer 3

UPDATE TableName SET ColumnName= ISNULL(ColumnName, 0 ) WHERE Id = 10

Answer 4

With coalesce:

coalesce(column_name,0)

Although, where summing when condition then 1, you could just as easily change sum to count - eg:

count(case when c.runstatus = 'Succeeded' then 1 end) as Succeeded,

(Count(null) returns 0, while sum(null) returns null.)

Answer 5

by following previous answers I was losing my column name in SQL server db however following this syntax helped me to retain the ColumnName as well

ISNULL(MyColumnName, 0) MyColumnName

Answer 6

When you want to replace a possibly null column with something else, use IsNull.

SELECT ISNULL(myColumn, 0 ) FROM myTable

This will put a 0 in myColumn if it is null in the first place.